IPA: /ˌæksɪˈmætɪk/
KK: /ˌæksɪˈɒmətɪk/
Something that is accepted as true or obvious without needing proof or explanation.
It is axiomatic that the sun rises in the east.
Axiomatic → It is formed from "axioma" (from Greek ἀξίωμα, meaning something that is worthy or self-evident) and the suffix "-tic" (meaning pertaining to). The word "axiomatic" refers to something that is self-evident or universally accepted without needing proof.
Think of something that is 'self-evident' or 'worthy' — that's what 'axiomatic' means, as it relates to a principle that is accepted without question.